1. Field of the Invention
The present invention relates to agricultural harvesters, and, more particularly, to driven shafts for agricultural harvesters.
2. Description of the Related Art
An agricultural harvester known as a “combine” is historically termed as such because it combines multiple harvesting functions with a single harvesting unit, such as picking, threshing, separating and cleaning A combine includes a header which removes the crop from a field, and a feeder housing which transports the crop matter into a threshing rotor. The threshing rotor rotates within a perforated housing, which may be in the form of adjustable concaves and performs a threshing operation on the crop to remove the grain. Once the grain is threshed it falls through perforations in the concaves onto a grain pan. From the grain pan the grain is cleaned using a cleaning system, and is then transported to a grain tank onboard the combine. When the grain tank becomes full, the combine is positioned adjacent a vehicle into which the grain is to be unloaded, such as a semi-trailer, gravity box, straight truck, or the like; and an unloading system on the combine is actuated to transfer the grain into the vehicle.
Typical unloading systems for combines involve unloading augers that are formed from inner and outer tubes (relative to the chassis of the combine) with rotatable augers inside that can be actuated to move grain longitudinally through the tubes. The tubes are pivoted to the combine so that they may be displaced laterally relative to the movement of the combine to an unload position in which grain is deposited in a wagon or other vehicle for transport. When the unloading function is completed, the auger tubes are retracted to a fold position in which the inner auger tube is generally parallel to the longitudinal axis of the combine and the outer auger tube is bent to an angle in a horizontal plane so that its free end is maintained within the overall configuration of the combine.
The auger tubes each have longitudinally extending augers within them that are mounted for rotation so that crop material is moved longitudinally through the augers. Because the auger tubes are pivoted between the unload and fold position, it is necessary to provide a mechanical coupling between the drive auger in the inner auger tube and the driven auger in the outer auger tube that delivers crop material to a transport vehicle. The coupling can be a first coupler, such as a cog, on the end of the auger shaft of the drive auger that has a complementary shape to a second coupler, which can also be a cog, on the auger shaft of the driven auger, so that the first cog abuts against the second cog during rotation of the drive auger to drive the driven auger.
When the drive auger and driven auger are pivoted apart then back together, the cogs can become separated from one another such that the first cog of the drive auger must be rotated nearly a full 360 degrees before abutting against the second cog of the driven auger. This rotation produces maximum potential rotational speed prior to abutment of the cogs and maximizes kinetic energy transfer over a short duration of time. This relative velocity of the two mating cogs upon impact creates a large impact force, which is then transmitted upstream through the drive system and can cause accelerated wear of drive and driven auger components.
What is needed in the art is an unloading auger with reduced rotational impact energy between the drive and driven couplers.